MUTAGENICITY OF COSMETIC PRODUCTS CONTAINING KATHON(R)

A variety of shampoos, conditioners, skin-care lotions, and other cosm etic products contain the biocide Kathon(R) CG, which is a mixture of two heterocyclic isothiazolinones: methylisothiazolinone and methylchl oroisothiazolinone. This mixture and the related biocide, Kathon(R) 88 6, have been shown to be potent sensitizers and bacterial mutagens. Fi ve cosmetic products that list the components of Kathon(R) on their la bels and two that do not were screened for mutagenicity with Salmonell a typhimurium TA100 without S-9. Five of these products and Kathon(R) 886 were further evaluated in TA100 without and with S-9. Kathon(R) 88 6, a cosmetic product that contained Kathon(R), and thin layer chromat ography-separated components of Kathon(R) 886 were identified by GC/MS analysis. Three of the five products that listed Kathon(R) were direc t acting mutagens with TA100. The remaining two products were consider ably more toxic than the other products and could not be evaluated For mutagenicity. The addition of S-9 reduced toxicity but did not elimin ate mutagenicity. The mutagenic evaluation of Kathon(R) 886 resulted i n a dose response similar to that seen with some cosmetic products but at a 1,000-fold lower concentration, and activity was also reduced by the addition of S9 mix. S9 reduced activity both with and without cof actors present. Thin layer chromatography separation of the components and subsequent identification by GC/MS indicated that methylisothiazo linone was nonmutagenic while methylchloroisothiazolinone was mutageni c. Additionally, a dichlorinated compound was identified which was als o mutagenic. In light of these findings and the re ported skin sensiti zation by Kathon(R) CG in various cosmetics, we recommend that additio nal testing be done to assure the safety of products containing Kathon (R) CG. (C) 1996 Wiley-Liss, Inc.